This invention relates to an ionizing radiation indicator mounted on an item of headgear as a safety device. More particularly, this invention relates to visual, audible, and tactile indicators incorporated into headgear, such as safety glasses, for dynamically displaying ionizing radiation levels in nearly real time, for use with ionizing radiation detectors which are mounted on the headgear or elsewhere on the body. Still more particularly, this invention relates to the combination of a circuit for detecting ionizing radiation in combination with a plurality of visual indicators mounted in the field of view of safety glasses to alert a wearer in nearly real time of the presence of ionizing radiation and its intensity. Audible, tactile, and infrared devices also coordinate to alert the wearer of unsafe levels of radiation.
Safety in ionizing radiation zones is of paramount importance. Central to safe conduct is the notion of monitoring levels of ionizing radiation and alerting personnel to those levels, especially when the levels become gradually or suddenly unsafe. Thus, a self-reading dosimeter is widely used in the nuclear industry for the immediate self-evaluation of X-ray, gamma ray, and beta radiation exposure to an individual. Such a device has significant shortcomings in that, at best, it is only periodically read by the wearer while in a potential radiation field. Frequently, such a dosimeter is carried at a location on the body of the wearer, or so shielded that the instrumentation does not accurately reflect the whole body exposure or the exposure for the head and vital organs. Many times, the dosimeter becomes contaminated from the gloves of workers and thereby provides an erroneous indication of higher exposure than actually received by the wearer. Moreover, its inherent fragility causes overexposure or fear of overexposure among workers because of some undetected physical blow or show to the instrument.
Representative examples of such instruments for measuring the amount of exposure to radioactivity are found in U.S. Pat. No. 2,638,553 to Landsverk; U.S. Pat. No. 4,320,393 to Engdahl; U.S. Pat. No. 4,695,730 to Noda; and U.S. Pat. No. 2,818,511 to Ullery. Engdahl also suggests that such a device might produce an acoustic or optical alarm when a threshold radiation level is reached. Noda suggests that the detector, which may be finger-mounted, may be separated from the alarm.
Miniaturized or pocket-sized radiation alerting devices intended to be carried on various parts of the body have been available for nearly two decades. These devices are commonly called "chirpers" because of the characteristic audible alerting signal emitted from the device upon exposure to a quantity of ionizing radiation. Frequently, within nuclear power plants, the overall decibel level of sound, or a frequency of sound similar to, or a harmonic of, the "chirp" exists as background sound from the various machines, fluid stream flows, and plant status signals which are endemic to electric power generation. Because of this background cacophony, the "chirper" alert signal is frequently nullified or goes unnoticed. "Chirpers" are therefore of limited use as worker alerting devices. A representative miniaturized radiation chirper is found in U.S. Pat. No. 4,197,461 to Umbarger.
Accordingly, it is a continuing problem in the nuclear arts to provide a person with a continuous awareness of his approximate current exposure to X-ray, gamma ray and beta ionizing radiation and to provide a multi-sensed alarm when an accrued dose in excess of the assigned daily safe exposure limit of the individual to those forms of radiation has been received. Thus, it is desired to visualize directly to a practical extent such otherwise insensible beta, gamma, and X-radiation. Moreover, it is also desired in this art to convert excessively intense radiation fields to audible and tactilely sensible stimuli as well as the visual indication, wherein the visual stimuli are continuously variable in response to the dynamic intensity of the ionizing radiation field or flux.
A hand-held gamma radiation dose meter having a Geiger-Muller (G/M) tube in circuit with a power supply and a pulse counter actuates flashing lights providing a visual display proportional to the counted pulses. However, the flash appears at the unit 13 itself, and not in the field of vision of its wearer. In U.S. Pat. No. 3,581,089, a system for nonvisible radiation detection comprising arrays of photosensitive detectors is suggested for incorporation into goggles or spectacles worn by an observer. However, such a system is not suggested for ionizing radiation, nor does it suggest visual and tactile sensors as herein contemplated. Other examples of headgear-mounted radiation warning devices may be found in U.S. Pat. No. 3,277,300 (infrared detector mounted on a helmet) or U.S. Pat. No. 2,818,511 (infrared and visible sensor mounted on a helmet).
None of these prior art devices has produced a desirable combination of an ionizing radiation sensitive device having a visual indicator in the field of view of the wearer and located in a non-distracting position. None has produced a device of the type described where the visual indicators flash to indicate in real time the current radiation level and none are accompanied in this combination with auxiliary warning devices, such as tactile, audible, and infrared warning devices.
Accordingly, it is a general objective of this invention to provide an item of headwear, such as a face protective or eye protective safety shield, which apparently converts otherwise humanly-insensible ionizing radiation and their dynamically varying intensities into a recognizable, definitive visual sensation.
It is another objective of this invention to provide an item of headgear which includes a plurality of visual indicators within the peripheral field of view of the wearer, and a circuit with an ionizing radiation detector to provide a real-time, continuous visual indication of ionizing radiation level.
It is another objective of this invention to provide an item of safety headgear, such as safety goggles, wherein ionizing radiation detectors, a power supply, amplifiers and interpreters are integrally mounted onto the headwear, such as on the frame or earpieces of safety glasses or goggles.
It is still another objective of this invention to provide an item of safety headgear, such as safety goggles or glasses, wherein ionizing radiation detectors and associated electronics are mounted together in a packet worn elsewhere by the use, and connected with the visual, tactile, and audible display devices on the goggles or glasses.
It is another overall objective of this invention to provide a simultaneous emergency alert through visual, audible, and tactile signals indicating unacceptably high levels of exposure to ionizing radiation.
It is still another overall objective of this invention to miniaturize the components of the system to a size suitable for non-obtrusive positioning on the frame or rims of safety spectacles or goggles which, upon the interaction of one or several of the forms of ionizing radiation with the sensor, produces a finite measurable electric impulse.
It is another overall objective of this invention to provide a visual lighting scheme which cycles repetitively in the view of the user through a circuit featuring a zener diode in circuit with a comparator and a display.
It is another general objective of the invention to locate the visual indicator where the wearer can see the indication without requiring body movement other than eye movement.
It is a further objective of the invention to utilize visible light spectrum-producing devices such as LED's and LCD's or other modulating or controlling devices.
These and other objectives of the invention will become apparent from a written description of the invention which follows taken in conjunction with the accompanying drawings.